CLAS physics database search results Measurement E151M691 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.65 126 -0.6924 0.6499 0.0519 0.65 222 0.0197 0.7098 0.03 0.65 282 0.064 0.676 0.0303 0.65 294 -0.5813 0.5723 0.0465 0.75 126 -0.3032 0.6295 0.0353 0.75 138 -1.4779 0.5101 0.0952 0.75 222 -0.1976 0.6094 0.0323 0.75 234 0.5269 0.6369 0.044 0.85 102 -0.1786 0.6578 0.0319 0.85 126 -0.4827 0.6388 0.0421 0.85 210 1.2074 0.628 0.0797 0.85 246 0.7015 0.7194 0.0524